#explain {
    width: 100%;
    height: 100px;
}
/*标题*/
#title{
    border: 0 solid #777171;
    border-bottom-width: 1px;
    width: 100%;
    margin-bottom: 20px;
    height: 70px;
    border-radius: 5px;
    padding: 25px;
    background-color: #f4f4f4;
    caret-color: transparent;
    /*opacity: 50%;*/
    text-align: center;
    /*font-weight: bold;*/
    font-size: 30px;
}

#title:focus{
    outline:none;
    border-bottom-width: 1px;
    font-size: 35px;
}

/*.input-group button{*/
/*    width: 200px;*/
/*    height: 100px;*/
/*}*/